1. Field of the Invention
The invention relates to an image forming apparatus having an automatic power-off function.
2. Related Background Art
Hitherto, from a viewpoint of a saving of energy, when no operation is performed for a predetermined time after completion of the image formation, an image forming apparatus activates an automatic power-off (automatic shut-off) function to automatically shut off a power source, thereby reducing a current supplying time to the image forming apparatus.
In recent years, even in an image forming apparatus of an ink jet system or an image forming apparatus of an electrophotographic system, there is an apparatus in which a warming-up time upon turn-on of the power source is short or an apparatus in which it can be almost immediately activated. Therefore, it is sufficient that a predetermined time which is required until the activation of the automatic power-off function is short. A waiting time until the image formation is enabled when the power source is again turned on is short. Therefore, even if the power source is frequently turned on and off, it is hardly troublesome. By such a function, a current supplying time to the image forming apparatus is reduced.
According to the image forming apparatus, however, there is a case where the image formation is interrupted during the image formation due to a cause of no paper or the like, the apparatus waits for the supplement of papers, and when the papers are supplemented, the image formation is again continued.
In such a case, since the automatic power-off time is short, in the image formation interrupted state, namely, when the image formation is interrupted due to the absence of papers, there is a case where the automatic power-off function is activated before the papers are supplemented, and the power source is turned off.
Particularly, there is a case where when the user is away from the apparatus during the image formation and is not aware of the interruption of the image formation due to the absence of papers or the like or it takes a long time to supplement the papers.
As mentioned above, when the automatic power-off function operates in the image formation interrupted state, in order to restart the image formation, the user must reset the set image forming mode (image formation copy quantity, zoom ratio, and the like).
Further, when images are formed from a plurality of originals by using an automatic document feeder (hereinafter, simply referred to as a feeder), there is a case where a few originals remain in the feeder because of the image formation interrupted state. In this state, the automatic power-off function operates. In order to restart the image formation by the user, the user has to remove the originals remaining in the feeder and to set the originals before the image formation interruption into the feeder.
Namely, when the automatic power-off function operates in the image formation interrupted state, since the power source is turned off in a manner similar to the ordinary turn-off of a power switch, when the user restart the image formation, the operation of the user is troublesome and there is a case where images are erroneously formed.